Light panel

ABSTRACT

A light panel which may be used from either side to produce two different lighting effects. The panel is a translucent sheet having a plurality of protuberances on one side and a plurality of indentations on the opposite side. Each of the protuberances has a plurality of plane surfaces intersecting the plane of the sheet, and each of the indentations has a plurality of plane surfaces also intersecting the plane of the sheet.

United States Patent Dr. Arthur D. Choyke, Jr.. Chicago, Ill.

Sept. 13, 1967 Feb. 23, 1971 Artcrest Products Co., Inc. Chicago, Ill.

inventor Appl. No. Filed Patented Assignee LIGHT PANEL 3 Claims, 8 Drawing Figs.

Int. Cl

Field of Search 240/78, 78 (LD), 78 (LD7), 106, 92

[56] References Cited UNITED STATES PATENTS 2,099,034 11/1937 Rolph 240/106 2,242,872 5/1941 Rolph.... 240/78(LD7) 3,113,728 12/1963 Boyd 240/9 1,194,294 8/1916 Johanson 240/106 3,163,367 12/1964 Bodian 240/106 Primary Examiner-Samuel S. Matthews Assistant ExaminerMonroe H. Hayes Attorney-Stone, Zummer & Livingston ABSTRACT: A light panel which may be used from either side to produce two different lighting effects. The panel is a translucent sheet having a plurality of protuberances on one side and a plurality of indentations on the opposite side. Each of the protuberances has a plurality of plane surfaces intersecting the plane of the sheet, and each of the indentations has a plurality of plane surfaces also intersecting the plane of the sheet.

LIGHT PANEL BACKGROUND OF THE INVENTION This invention relates to an improved article of manufacture, and specifically, a light panel.

Light panels are customarily used with one or more fluorescent tubes for various purposes. The light panels are used to enhance the overall appearance of a lighting installation by placing fluorescent tubes of out of direct view. The light panels are also perform functions of acting as lenses of various configurations to product various lighting effects, such as reducing glare.

customarily, light panels are sold through distributors who stock light panels of various sizes and types. In view of a large number of designs used on light panels, a distributor requires a substantial amount of space and capital to store all types of light panels.

Once a light panel is installed in a given installation, in order to change the lighting effect of the installation, it is necessary to discard the light panel and substitute another light panel. Although lighting design is approaching a rigorous science, once a particular panel is selected, it still be may be found, after the actual installation is made and actual use is made, that certain changes are required. Thus, it becomes necessary either to discard the light panels or to accept certain inadequacies of the panel.

SUMMARY OF THE INVENTION The subject of the invention relates to a light panel which is made of a translucent material and is particularly adaptedto be manufactured of a translucent plastic material. The instant construction of the light panel is such that a single light panel may be utilized to give two different lighting effects. It is a principal object of this invention to provide a light panel which produces one effect when the light source is positioned on one side of the light panel and a second effect when the light source is positioned on the other side of the light panel.

It is a further object of the present invention to provide an improved light panel construction which produces a high light transmission rate when one side is positioned adjacent to a light source and a glare reduction panel when the same panel is reversed and the opposite side is placed adjacent to the light source.

It is a still further object of the hereindisclosed invention to provide an improved light panel construction wherein the light panel may be simply and economically manufactured.

Other objects and uses of the instant invention will become readily apparent to those skilled in the art upon a perusal of the following specification in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS F l6. 1 is a side elevational view of a portion of a lighting installation showing an elongated fluorescent tube mounted in the fixture with a light panel embodying the present invention positioned below the tube;

FIG. 2 is a plan view of a portion of one side of a light panel embodying the hereindisclosed invention;

FIG. 3 is a fragmentary view of a portion of the opposite side of the light panel shown in FIG. 2;

FIG. 4 is an enlarged cross-sectional view of the light panel ofFlGS. 1,2 and 3;

FIG. 5 is an enlarged plan view of the side of the panel shown in FIG. 2, showing the details of the indentations of the panel;

FIG. 6 is an enlarged plan view of the protuberances of FIG. 3, showing the random alignment of the protuberances and the planes of the protuberances;

P16. 7 is an enlarged cross-sectional view showing a plane of the light panel with arrows representing light rays; and

FIG. 8 is similar to FIG. 7, but with the light rays passing through the light panel from the other side thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and especially, to FIG. 1, it may be seen that a light panel generally indicated by numeral 10 and embodying the hereindisclosed invention is shown supported by a frame 12 adjacent to a conventional elongated fluorescent tube 14, which is supported by a conventional fix- :ure 16. As is conventional, the tube 14 emits light which passes through the panel 10.

The panel 10 is a relatively thin sheet of rigid plastic, which in this case is polystyrene. However, other suitably material may be used, such as, acrylic, Lucite or a combination of acrylic and polystyrene.

As may be seen in FIGS. 2,4 and 5, one side of the panel 10 has a plurality of indentations 18, which indentations are regularly aligned to form a grid face on the surface of the light panel; as may be best seen in FIG. 2. Looking now to FIG. 5, it may be seen that each indentation is formed by four flat triangular sides 20 which define a pyramid. The plane of each of the sides intersects theadjacent plane defined by the adjacent surface of the panel at an angle of 37.Inasmuch as the panel is in this instance flat, the angle of 37 is also the angle between the plane of each of the sidesand the plane of the panel.

As may be seen in FIGS. 3,4, and 6, the other side of the panel has a plurality of randomly aligned and random sized protuberances 22 formed on .the surface of the panel. Each of the protuberances is formed by a plurality of random flat sides 24, as may be best seen in FIG. 6. Each of the flat sides 24 defines a plane which intersects the plane defined by the ad-. jacent surface of the panel-at an angle no greater than 15. However, the angles vary with each protuberance. The intersection of the sides forming the tops of the protuberances is slightly rounded so that there are no sharp edges at the intersection of the sides.

The maximumheightof each of the protuberances 22 is one-fourth of the thickness of the panel, and the maximum depth of each of the indentations 18 is one-half of the maximum thickness of the panel.

When the side of the panel having the randomly arranged protuberances is placed adjacent to the light source, one lighting effect is produced, and when the side having the regular indentations is placed adjacent to the light source, a different lighting effect is produced.

Looking now to FIG. 7, which is a plane cross-sectional view through a portion of the panel 10, various light rays are shown therein and also'shown is how the light rays are bent by the panel and emitted therefrom to produce a particular lighting effect. Considering first light ray 26, which is represented by solid lines, the light ray is emitted from tube 14 perpendicular to the plane of the panel. The light ray strikes side 24a of a protuberance 22a and is bent slightly to follow ray path 26a due to the index of refraction of the material; Light ray 26a then strikes the side 20a of an indentation 18a, and as the light ray passes from the material of the panel into air, the index of refraction of the material causes the light ray to be bent as shown as light ray 26b.

A secondlight ray 28, whichis represented by a dot-dash line, is shown parallel to light ray 26, and it may be seen that when the light ray strikes another side 24b of the protuberance, light ray 28 is bent to ray path 284. As the light ray 28a leaves the material at side 20b, the light ray is bent to follow the path of light ray 2815, which is divergent to the path of light ray 26b. It may be seen that there is a divergence of parallel light rays which is caused by the differences in the angles of the surfaces and the index of refraction of'the material.

A third light ray 30, which is represented by a broken line, is shown engaging a top or flat surface of the protuberance 22. Since the light ray is perpendicular to the surface, the light ray 30a passes through the material of the light panel without being bent. However, when the light ray passes from the material of the panel into the air at side 20a, it is bent to follow light ray 30b. It may be appreciated that as the angles of the.

faces of the protuberances vary between 15 and a horizontal surface, there is a variance in the direction of emission of the light rays so that there is a reduction of glare from the light emitted in view of the fact that the light rays are dispersed into various paths.

It may be appreciated that all of the light rays emitted by the light source are not perpendicular to the plane of the light surface, but rather, some of the light rays come in at varying angles to the light panel. A fourth light ray 32, which is represented by a double dot-dash line, is shown. This particular light ray 32 is at an angle of 35 to the normal of a surface of the protuberance. As this light ray passes from air into the material of the panel, the light ray is bent to follow path 32a .Light ray 32a strikes a side 200 of an indentation at an angle to the normal to the plane surface of sideltlc which is greater than the critical angle of the material so that light ray 32a then follows a path 32b through the material until it strikes side 24b of the protuberance, and again, the angle between the normal to the surface and the light ray 32b is greater than the critical angle so that the light ray is reflected to follow path 32c and the light ray then strikes a surface of a side 20d of an indentation at an angle to the normal of a surface which is less than the critical angle, and as the light ray passes from the panel into air, it is bent to path 32d. Thereby, the light ray is bounced within the light panel. It maybe appreciated that this bouncing of light rays within the panel and the bending of the light rays gives an observer a crystalline effect when the observer looks at the panel from an angle which aligns the observer along a path such as light path 32d or 30b. It may be further appreciated that this dispersion of light rays causes the observer to see some portions of the panel which appear to be bright and others dark, thereby producing an effect of a panel which has a multitude of bright spots in a field of dark, and the slightest movement on the part of the observer causes certain light spots to appear dark, since the light rays no longer reach the observer, and other dark spots to become bright, and thereby producing a glittering effect if the observer moves relative to the light panel. Thus, positioning of the side of the panel having a plurality of protuberances adjacent to the light source provides a lighting effect which has a minimum amount of glare, and observation of the panel produces the effect that the panel glitters if the observer moves slightly.

Turning now to a consideration of HG. 8, in FIG. 8 a section is shown wherein the protuberances are spaced away from the light source and the indentations are spaced adjacent to the light source. A fifth light ray 34 is shown entering the light panel through side 20b, which light ray 34 is bent to path Ma. The light ray 34a then passes through side 24b to follow path 34b. A sixth light ray 36 is shown passing tr through side 20a then following path 36a until it passes into the air through side Z ta to follow path 36b. It may be seen that the divergence between the light rays 34b and 36b is less than the divergence between light rays 26b and 28b. A seventh light ray 38 is shown entering the panel at side 20b and is bent to path 38a which is parallel to path 34a .However, the light ray 38a enters the air through a surface 23 which is parallel to the surface of the panel and is bent to follow path 38b. An eighth light ray 40 is shown entering the panel at side 20c and is bent to follow path 4%. The light ray 40a leaves the panel through a side 24c of a protuberance to be bent to follow path 40b.

it may be noted by a comparison of H68. 7 and 8 that the light rays are not dispersed as greatly when the indentations are positioned adjacent to the light source as when the protuberance are placed adjacent to the light source. Therefore, the

positioning of the indentations adjacent to the tube creates a greater intensity of light directly under the light source since there is less dispersion of light rays. However, there is sufiicient dispersion of light rays to provide some glare reduction.

It may also be appreciated that inasmuch as there is less dispersion of the light rays when the indentations are adjacent to the light source, there is a substantial reduction of the appearance of glitter of the light panel inasmuch as most of the light rays are directed in a downward direction, rather than at an les to the plane of the li t panel.

t may be seen from the oregomg that the panel 10 may be used to provide two different lighting effects simply by using one side or the other of the panel. When the panel is used so that the protuberances are adjacent to the light source, the panel has a high dispersion of light rays and provides a gemlike or crystalline effect for a viewer stationed at an angle to the panel. When the panel is reversed so that the indentations are positioned adjacent to the light source, the panel produces a lighting effect having a higher intensity of light below the light panel with some reduction of glare inasmuch as the light is dispersed but not to a high degree.

Although a specific description of the instant invention has been shown and described above, it is readily apparent that those skilled in the art may make various modifications and changes in the present construction, such as, changing materials, varying the angles of the plane surfaces and varying the sizes and numbers of indentations. It is to be expressly understood that the instant invention is limited only by the appended claims.

lclaim:

l. A translucent sheet for use as a reversible light panel having a plurality of randomly positioned protuberances on one surface, each of said protuberances having a random number of plane surfaces, each of said plane surfaces defining a random angle with the adjacent surfaceof the sheet, each of the protuberances having its upper portion rounded, and a plurality of regular indentations formed on the opposite surface of the sheet, each of the indentations being formed by four plane surfaces, each of the plane surfaces of the indentations defining a given angle with the adjacent opposite surface of the sheet, said indentations being aligned to have the edges of the indentations form straight lines with the adjacent surface of the sheet, each of the indentations having its depth from the respective adjacent surface of the sheet greater than the height of the highest protuberance above the respective adjacent surface of the sheet, whereby a light source positioned on one side of the sheet produces a given type optical effect when the sheet is viewed from the other side, and a light source positioned on the opposite side of the sheet produces another type optical effect when the sheet is viewed from the one side.

2. A translucent sheet for use as a reversible light panel as defined in claim 1, wherein the angle of the plane surface of the indentation with the adjacent surface of the sheet is greater than the angle between the plane surface of the protuberance with the adjacent surface of the sheet.

3. A translucent sheet for use as a reversible light panel as defined in claim 1, wherein the angle between the plane surface of the indentation and the respective adjacent surface of the sheet is at least twice as great as the largest angle between the plane surface of a protuberance and the respective adjacent surface of the sheet.

"H UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,566,102 Dated Febg arv 2;, 1971 Inventofls) Arthur D. Choyke, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Please cancel "Dr. Arthur D. Choyke, Jr. as the invent and substitute --Arthur D. Choyke, Jr.

Column 1, Line 11, cancel "are" Column 1, Line 23, begin a new paragraph.

Column 2, Line 11, "suitably" should be suitable--.

Column 2, Line 54 remove. italicized words and substitu regular type.

Column 2 Line 74 "15" should be --l5--.

Column 3, Line 11, insert at end of line.

Column 3, Line 12, cancel at beginning of line. Column 3, Line 18, insert after "320". I

Column 3, Line 48, cancel "tr" Column 3, Line 49, insert after "20a".

Column 3, Line 53, insert after "38a" Column 3, Line 63, "protuberance" should be -protubera Signed and sealed this 29th day of June 1971 (SEAL) Attest:

EDWARD M.FLETGIER,JR. WILLIAM E. SCHUY] Attesting Officer Commissioner of 1 

1. A translucent sheet for use as a reversible light panel having a plurality of randomly positioned protuberances on one surface, each of said protuberances having a random number of plane surfaces, each of said plane surfaces defining a random angle with the adjacent surface of the sheet, each of the protuberances having its upper portion rounded, and a plurality of regular indentations formed on the opposite surface of the sheet, each of the indentations being formed by four plane surfaces, each of the plane surfaces of the indentations defining a given angle with the adjacent opposite surface of the sheet, said indentations being aligned to have the edges of the indentations form straight lines with the adjacent surface of the sheet, each of the indentations having its depth from the respective adjacent surface of the sheet greater than the height of the highest protuberance above the respective adjacent surface of the sheet, whereby a light source positioned on one side of the sheet produces a given type optical effect when the sheet is viewed from the other side, And a light source positioned on the opposite side of the sheet produces another type optical effect when the sheet is viewed from the one side.
 2. A translucent sheet for use as a reversible light panel as defined in claim 1, wherein the angle of the plane surface of the indentation with the adjacent surface of the sheet is greater than the angle between the plane surface of the protuberance with the adjacent surface of the sheet.
 3. A translucent sheet for use as a reversible light panel as defined in claim 1, wherein the angle between the plane surface of the indentation and the respective adjacent surface of the sheet is at least twice as great as the largest angle between the plane surface of a protuberance and the respective adjacent surface of the sheet. 